The Internet has become a popular tool for sending and receiving information. In essence, the Internet comprises a worldwide network of communications equipment and service providers, which use a common protocol for communicating. On the Internet, messages are transmitted from one user to another over a vast infrastructure of routers, servers, gateways and other similar devices. Typically, users on either end of the network operate computers equipped with appropriate software, devices and other components. Examples of such components include a modem and Internet browser application. Often, a user establishes a connection to the Internet through an Internet Service Provider (ISP). The underlying link level protocol stacks handle the messaging functions on both ends of the channel.
With most Internet Protocol (IP) applications, the network routes messages from one user to another using the IP address of the intended recipient. Thus, the physical address, phone number and other geographic location indicators are not critical to the message routing functions in an IP network. On the other hand, other communications mediums, such as the Public Switched Telephone Network (PSTN), support connections by tying a user with his or her phone number. An example are the Public Service Access Points (PSAPs) which support a network of emergency call answering centers throughout the United States. With such centers, the user is able to get emergency assistance by dialing a special number such as 9-1-1. The PSTN routes the call to the appropriate center serving the emergency zone of the caller based on their phone number. The center, in turn, dispatches the appropriate emergency personnel to the caller's location.
At the same time, the widespread use of the Internet as a communications tool has led to an intense push for the integration of Internet services with those offered through the existing telecom infrastructure of the PSTN.